1. Field of the Invention
The present invention relates to a coaxial connector used for portable, small electronic equipment or the like and, more particularly, to a coaxial connector which has a movable terminal and a fixed terminal disposed in an insulating case thereof so that the movable terminal and the fixed terminal are connected to or disconnected from each other as a mating coaxial connector is attached thereto or detached therefrom.
2. Description of Related Art
A conventional coaxial connector used for portable communications equipment such as a portable telephone has a construction shown in FIG. 11, for example. A conventional coaxial connector 80 has a fixed terminal 83 and a flexible movable terminal 84 provided in a cavity 82 of a cylindrical insulating case 81. The fixed terminal 83 and the movable terminal 84 have the left ends thereof fixed and they respectively extend rightward along the top and bottom surfaces of the cavity 82 as illustrated in FIGS. 11 and 12. A predetermined interval is provided between the fixed terminal 83 and the movable terminal 84 at their fixed ends. Provided on the outer surface of the insulating case 81 is a cylindrical outer terminal 86 which is disposed in close contact with a cylindrical peripheral surface 85 of the insulating case 81. Also, an additional component 89 is located on the outside of the coaxial connector 80 to make it flat and square.
When no mating coaxial connector is attached to this coaxial connector 80, the urging force of the flexible movable terminal 84 holds itself in contact with the fixed terminal 83. When a mating coaxial connector is attached to the coaxial connector, the movable terminal 84 is pushed up by a central contact 88 of a mating coaxial connector, which has been introduced through an inlet 87 of the coaxial connector 80, and disconnected from the fixed terminal 83, bringing the central contact 88 into contact with the movable terminal 84 as shown in FIG. 12. When the mating coaxial connector is attached, an outer conductor, not shown, of the mating coaxial connector is brought into contact with the external terminal 83 of the coaxial connector 80.
In the foregoing conventional coaxial connector 80, however, the fixed terminal 83 and the movable terminal 84 are so disposed that they are axially aligned and serially positioned with the central contact 88 of the mating coaxial connector, making it impossible to reduce the lateral dimension of the coaxial connector 80 from the sum of the full length of at least the fixed terminal 83 and the full length of the central contact 88. This has posed a problem in that it is difficult to reduce the length as well as thickness of the coaxial connector 80, failing to fulfill the demand for further compacted portable communications equipment and the like.
An attempt to reduce the size of a coaxial connector with the construction illustrated in FIG. 11 would require that the dimension of the inlet 87 through which the central contact 88 is introduced be reduced. This, however, would inevitably make smaller the interval between the fixed and movable terminals 83 and 84 when they are set apart from each other, presenting a problem of insufficient electrical isolation between the fixed and movable terminals 83 and 84 against high-frequency signals.
The difficulty of reducing the thickness is attributable to a considerable distance LY provided to set the fixed terminal 83 and the movable terminal 84 apart vertically; the distance LY must be added to the thickness of the coaxial connector 80, thus preventing the reduced thickness from being achieved. The thickness would be of course reduced by reducing the distance LY; however, doing so would make the fixed terminal 83 and the movable terminal 84 closer, resulting in inadequate electrical isolation between the fixed terminal 83 and the movable terminal 84 against high-frequency signals when they are in a disconnected state as described above. This means that the reduction in the thickness is unlikely to be accomplished by shortening the distance LY in a practical coaxial connector.
The present invention has been made with a view toward solving the foregoing problems, and it is an object thereof to provide a coaxial connector which ensures reliable, stable contact and permits sufficient reduction in size and thickness compared to the prior art.
To this end, according to the present invention, there is provided a coaxial connector including:
an insulating case having a cavity for accommodating at least a central contact of a mating coaxial connector;
an internal terminal, in the cavity of the insulating case, including a fixed terminal and a movable terminal positioned to be connected to and disconnected from each other, a portion of at least the movable terminal projecting approximately at a right angle to an axis of the central contact of the mating connector accommodated in the cavity;
an elastic member located between a bottom surface in the cavity of the insulating case and the movable terminal such that the elastic member is compressed under pressure applied by the movable terminal when the central contact of the mating connector is accommodated in the cavity of the insulating case; and
an external terminal on an outer surface of the insulating case and which comes in contact with the outer conductor of the mating connector when the mating connector is attached to the insulating case;
wherein the movable terminal of the internal terminal is urged in a direction opposite to the introducing direction of the central contact by at least an elastic force of the elastic member such that the fixed terminal comes in contact with the movable terminal and both terminals come into conduction when the central contact of the mating connector not is accommodated in the cavity of the insulating case, and wherein the central contact introduced in the cavity pushes the movable terminal down toward a bottom surface of the cavity to cause the movable terminal to be detached from the fixed terminal when the central contact of the mating connector is accommodated in the cavity of the insulating case.
In a preferred form of the present invention, the projecting portion of at least the movable terminal and a projecting portion of the fixed terminal of the internal terminal are spaced by a predetermined distance from the bottom surface in the cavity such that the projecting portions are approximately opposed to each other.
In another preferred form of the present invention:
the insulating case can have an approximately hexahedron shape;
the lead sections of the movable terminal and the fixed terminal can extend to a rear of the insulating case to provide connection ends nearly flush with the rear surface of the insulating case; and
the external terminal can be a plate-like member which is attached to the insulating case and which has an approximately U-shaped longitudinal cross-section comprising a central flat section and two bent sections, a through-hole for receiving a mating coaxial connector into the cavity of the insulating case at the central flat section which covers the top surface of the insulating case, and the bent sections on both sides of the flat section extending to the rear of the insulating case along the outer surface of the side walls of the insulating case to provide connection ends nearly flush with the rear surface of the insulating case.
In still another preferred form of the invention, the insulating case is formed integrally with the external terminal.
In yet another preferred form of the invention, the elastic member is a rubber elastic member, or a spring including a helical coil spring.
Unlike the conventional example as shown in FIG. 11 and FIG. 12, both the movable and fixed terminals are disposed nearly at right angles to the central contact of the mating coaxial connector rather than being disposed in parallel direction thereto. Thus, the total length of the terminals and the central contact does not adversely affect an effort to reduce the-dimension of the coaxial connector.
Further, the interval between the movable terminal and the fixed terminal when they are separated is equal to the moving amount of the movable terminal when it is pushed in by the central contact toward the bottom surface. Therefore, even when the whole coaxial connector is made smaller, a sufficient interval can be secured between the two terminals when they are not in contact, by setting an appropriate point reached by the distal end of the central contact.
Moreover, the movable terminal and the fixed terminal are brought and held in contact by the elastic force of the compressed elastic member in addition to the spring force of the movable terminal. This enables an improved force of the contact between the fixed terminal and the movable terminal, permitting reduced contact resistance. The movable terminal does not solely depend on the spring force thereof to accomplish contact with the fixed terminal; therefore, even when the movable terminal is made shorter and the spring force of the movable terminal is decreased, it will be securely brought in contact with the fixed terminal by the elastic force of the elastic member. Thus, the movable terminal can be made even shorter.
In short, owing to the operations described above, in comparison with the conventional example, stable and positive contact between the movable terminal and the fixed terminal can be achieved, and markedly reduced size and thickness can also be accomplished.
The movable terminal and the fixed terminal are disposed to be opposed to each other rather than disposing them vertically as in the conventional example shown in FIG. 11 and FIG. 12. Therefore, it is no longer necessary to install the movable terminal and the fixed terminal vertically with a large interval allowed therebetween, and the disposition of the fixed terminal and the movable terminal does not affect an effort to reduce the thickness of the coaxial connectors. For easier understanding, this aspect will be described with reference to the conventional coaxial connector 80 shown in FIG. 12. In the case of the present invention wherein the movable terminal and the fixed terminal are disposed to face against each other, a fixed terminal 83 will be located at contact point P, i.e. at the same height as that of the movable terminal 84. This enables the thickness to be reduced by distance LZ.
Shaping the insulating case into the nearly hexahedron and attaching the flat section of the external terminal to the top surface of the insulating case enable easier mounting by a chip placer, thus making the present invention even more effective.
Easier surface mounting can be fulfilled by extending both bent sections of the external terminal and the lead sections of the fixed terminal and the movable terminal to the bottom of the insulating case to provide the connection ends nearly flush with the rear surface of the insulating case.
Forming the insulating case integrally with the external terminal makes it possible to fabricate the insulating case while assembling the insulating case and the external terminal at the same time. This permits reduction in manufacturing cost.